Laars MASCOT LX Installation And Operation Instructions Manual

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LAARS Heating SystemsPage 389.7.1 Cascade Manual ConfigurationIn some applications it may be necessary to configure thecascade system manually. To do this, the boilers shouldbe wired as shown in the Auto Cascade section of themanual. Then each individual control in the cascademust have a specific address assigned by adjusting P06“ Cascade address” on each boiler. To start, identifythe boiler that will be the “master” boiler. Navigate toparameter P06 “cascade address” set to “0” and press“Select” (do NOT press and hold select). Then press andhold select.Repeat this process for each boiler in the cascade settingeach address to a unique number.The last step is to adjust all of the setpoints for theinstallation application as shown in the Auto cascadesection of the manual.9.7 Cascade Auto ConfigurationTo operate up to 8 boilers in cascade, the boilersmust be “daisy chained” together using Modbusterminals A, B and GND, located on the boilersterminal block. The wiring should be completed with atleast three wire shielded cable with ground. The groundwire should be connected to a suitable chassis groundon one end of the daisy chain only. Wire each boilersterminal A in series with the next boilers terminal Auntil all are connected. Repeat this process for TerminalB and GND.To configure the control system, identify whichboiler is going to be the “master” boiler for the cascadesystem and navigate to installer parameter P06,“Cascade Address”. Set the address to “0” and pressand hold “select”. When “auto cfg” appears on thedisplay press “select” to start the auto configurationprocess. The auto configuration process will find allboilers connected to the “master” boiler and assignaddresses. When auto configuration is complete thedisplay should show “boilr #” where # is the totalnumber of boilers found in the cascade system.The final steps are to set the individual setpointsin the cascade system, which include P07 “CascadeSetpoint”, P08 “Cascade off Hysteresis” and P09“Cascade on hysteresis”. These variables must be setto the appropriate values for the installation. Whensetting P09 “cascade on hysteresis” the value shouldNOT be less than P08 “Cascade off Hysteresis” asP09 references the off point (P07+ P08) as the startingpoint for the on hysteresis. An example of this is shownbelow.Correct settings:P07 = 120°FP08 = 10°FP09 = 20°FWith these setting the modulation point is 120°FThe off point is 120°F + 10°F = 130°FThe on point is 130°F – 20°F = 110°FIncorrect settings:P07 = 120°FP08 = 10°FP09 = 5°FWith these setting the modulation point is 120°FThe off point is 120°F + 10°F = 130°FThe on point is 130°F – 5°F = 125°FIn this case the boiler is turning back on prior toreaching the modulation point, which could lead toshort cycling.